pub fn main() {
    let r;
    {
        let x = 5;
        r = x;
    }
    println!("r: {}", r);
    println!("{}", longest("aa", "aaaaa"));
}

// fn longest(a: &str, b: &str) -> &str {
fn longest<'a>(a: &'a str, b: &'a str) -> &'a str {
    if a.len() > b.len() {
        a
    } else {
        b
    }
}